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Article

Geologica Carpathica, 1996, vol. 47, no. 2
FORAMINIFERAL ASSEMBLAGES: INDICATORS OF THE PALEOENVIRONMENTAL EVOLUTION OF MARINE BASINS AND EUSTATIC CHANGES (KISCELLIAN-KARPATIAN OF THE SOUTH SLOVAK AND DANUBE BASINS)
Abstract
The results of paleoecological analysis of the foraminiferal assemblages enabled estimation of oscillations of O2- content, salinity, paleodepth and sediment supply from the Upper Kiscellian to the Karpatian in the South Slovak, Danube and partly the Eastern Slovak Basins. These conclusions have been used for reconstruction of eustatic changes in the analysed area. The local oscillations have been correlated with the global eustatic changes. The global cycles manifested themselves in the semi-closed Central Paratethys basins. There are differences in the amplitude of the oscillations (in the whole studied interval), and in the timing of the initiation (the Upper Ottnangian, the Karpatian) and the termination (the Upper Egerian) of the cycles between the hinterland and frontal part of the Western Carpathians. From the differences in amplitude the timing of initiation of global and local cycles and the changes in sediment supply, the Kiscellian-Eggenburgian and the Upper Ottnangian-Karpatian tectonic cycles can be distinguished in the hinterland and the Eggenburgian-Ottnangian and the Karpatian cycles in the frontal part of the Western Carpathians. The global cycles with low amplitude of sea level rise correlate with the periods when the low-oxic environment was recognized in the whole basin (the Kiscellian, the Ottnangian) or in the deepest part of the basin (the Egerian) can be correlated with the global eustatic lowerings. A hyposaline environment was widespread at the beginning of significant transgressions (Lowermost Eggenburgian, Lowermost Karpatian). Changes in numbers of the foraminiferal species reflect significant sea-level changes. High percentages of new planktonic species characterise the widespread transgressions (the Eggenburgian, the Karpatian). Regressions connected with enclosing of basins are accompanied by decreases in species numbers (the Upper Egerian, the Ottnangian).
Pages:
119 - 130
Published online:
0. 0. 1996